Sealant compositions comprising colloidally stabilized latex and methods of using the same

ABSTRACT

Sealant compositions comprising a colloidally stabilized latex and methods of using the same to service a wellbore are provided. The sealant compositions may include: an aliphatic conjugated diene monomer; an additional monomer comprising a non-aromatic unsaturated mono- or di-carboxylic ester monomer, an aromatic unsaturated monomer, a nitrogen-containing monomer, or combinations thereof; and a protective colloid. The foregoing sealant composition may be displaced into the wellbore to isolate the subterranean formation from a portion of the wellbore, to support a conduit in the wellbore, to plug a void or crack in the conduit, to plug a void or crack in a cement sheath disposed in an annulus of the wellbore, to plug an opening between the cement sheath and the conduit, or combinations thereof. The colloidally stabilized latex remains substantially stable when exposed to salt, which may be present in the wellbore and/or in the sealant composition itself.

FIELD OF THE INVENTION

This invention generally relates to sealant compositions for use in awellbore. More specifically, the invention relates to sealantcompositions comprising colloidally stabilized latex and methods ofusing such compositions to service a wellbore.

BACKGROUND OF THE INVENTION

Natural resources such as gas, oil, and water residing in a subterraneanformation or zone are usually recovered by drilling a wellbore down tothe subterranean formation while circulating a drilling fluid in thewellbore. After terminating the circulation of the drilling fluid, astring of pipe, e.g., casing, is run in the wellbore. The drilling fluidis then usually circulated downwardly through the interior of the pipeand upwardly through the annulus, which is located between the exteriorof the pipe and the walls of the wellbore. Next, primary cementing istypically performed whereby a cement slurry is placed in the annulus andpermitted to set into a hard mass (i.e., sheath) to thereby attach thestring of pipe to the walls of the wellbore and seal the annulus.Subsequent secondary cementing operations may also be performed. Oneexample of a secondary cementing operation is squeeze cementing wherebya cement slurry is employed to plug and seal off undesirable flowpassages in the cement sheath and/or the casing. While a cement slurryis one type of sealant composition used in primary and secondarycementing operations, other non-cement containing sealant compositionsmay also be employed.

Latex emulsions, which contain a stable water-insoluble, polymericcolloidal suspension in an aqueous solution, are commonly used insealant compositions to improve the properties of those compositions.For example, latex emulsions are used in cement compositions to reducethe loss of fluid therefrom as the compositions are being pumped to theannulus. Latex emulsions are also employed to reduce the brittleness ofthe sealant compositions; otherwise the compositions may shatter underthe impacts and shocks generated by drilling and other well operations.Such sealant compositions may be used for sealing the junction ofmultilateral wells. In addition, latex emulsions are used to improve theflexibility of sealant compositions.

Additionally, latex emulsions are utilized to prevent gas migrationduring a transition phase in which the sealant composition changes froma true hydraulic fluid to a highly viscous mass showing some solidcharacteristics. When first placed in the annulus, the sealantcomposition acts as a true liquid and thus transmits hydrostaticpressure. During the transition phase, certain events occur that causethe sealant composition to lose its ability to transmit hydrostaticpressure such as the development of a solid (i.e., stiff) structure inthe composition. When the pressure exerted on the formation by thesealant composition falls below the pressure of the gas in theformation, the gas initially migrates into and through the composition.The gas migration causes flow channels to form in the sealantcomposition, and those flow channels permit further migration of the gasafter the sealant composition sets.

Moreover, latex emulsions are also mixed with drilling fluids,particularly the non-aqueous type, near loss-circulation zones such asnatural or induced fractures, thereby forming solid masses for sealingthose zones to prevent the drilling fluids from being lost duringdrilling.

Traditional latex emulsions prepared by emulsion polymerization usuallybecome unstable in the presence of salt. That is, the polymer particlescontained in the latex typically fall out of the aqueous solution andform a separate rubbery phase when exposed to salt. Unfortunately,sealant compositions often come into contact with salts that arenaturally present in the wellbore. Further, the sealant compositionsthemselves often contain salts of monovalent, divalent, and occasionallytrivalent cations. They may even be saturated with such salts to ensurethat they do not wash out or dissolve salt zones located in thesubterranean formation. To improve the tolerance of latex emulsions insealant compositions to salts, especially those containing monovalentand divalent cations, surfactants such as ethoxylated nonylphenolsulfates are included in the compositions. The use of such surfactantsin the sealant compositions undesirably increases the overall cost ofconstructing and maintaining the wellbore. A need therefore exists touse latexes in sealant compositions, such as cement slurries, that arestable in the presence of salts.

SUMMARY OF THE INVENTION

Sealant compositions for use in a wellbore comprise a colloidallystabilized latex. The colloidally stabilized latex may include: analiphatic conjugated diene monomer; an additional monomer comprising anon-aromatic unsaturated mono- or di-carboxylic ester monomer, anaromatic unsaturated monomer, a nitrogen-containing monomer, orcombinations thereof; and a protective colloid. In an embodiment, thesealant compositions may include a cement slurry.

Methods of servicing a wellbore comprise displacing the foregoingsealant composition into the wellbore. The sealant composition may bepositioned in the wellbore to isolate the subterranean formation from aportion of the wellbore, to support a conduit in the wellbore, to plug avoid or crack in the conduit, to plug a void or crack in a cement sheathdisposed in an annulus of the wellbore, to plug an opening between thecement sheath and the conduit, to prevent the loss of drilling fluidinto a void or crack in the formation, or combinations thereof. Thecolloidally stabilized latex remains substantially stable when exposedto salt, which may be present in the wellbore and/or in the sealantcomposition itself.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with an embodiment, sealant compositions for use in awellbore that penetrates a subterranean formation comprise a colloidallystabilized latex. It is understood that “subterranean formation”encompasses both areas below exposed earth or areas below earth coveredby water such as sea or ocean water. As used herein, “colloidallystabilized latex” refers to a latex comprising polymer particlessuspended in an aqueous solution and at least one protective colloid forproviding stabilization to the colloidal polymer emulsion. Thecolloidally stabilized latex may be employed in a sealant composition tocontrol fluid loss from the composition, to improve gas migrationpotential, to improve the flexibility or elasticity of the setcomposition, to improve the properties of the composition such ascompressive strength, tensile strength, and rheology, to preventdrilling fluid losses, to seal junctions in multi-lateral wells, totemporarily plug loss-circulation zones in remedial operations, and soforth.

Protective colloids known in the art may be employed in the colloidallystabilized latex. Examples of suitable protective colloids include, butare not limited to, partially and fully hydrolyzed polyvinyl alcohols,cellulose ethers such as hydroxymethyl cellulose, hydroxyethylcellulose, hydroxypropyl cellulose, starch and starch derivatives, andcarboxymethyl cellulose, natural and synthetic gums such as gumtragacanth and gum arabic, polyacrylic acid, acrylates, poly(vinylalcohol)co(vinyl amine) copolymers, and combinations thereof.

Examples of suitable colloidally stabilized latexes for use in thesealant compositions and methods of making such latexes are described inU.S. Pat. Nos. 5,900,451 and 6,130,287, both of which are incorporatedby reference herein in their entirety. In those patents, the colloidallystabilized latexes are referred to as “stabilized emulsion polymers.” Inaddition, examples of suitable commercially sold colloidally stabilizedlatexes include BS 2100 latex (i.e., carboxylated butadieneacrylonitrile latex) available from Dow Reichhold Inc. As would berecognized by one skilled in the art, the dry form of such colloidallystabilized latexes may also be employed.

In an embodiment, the polymer contained in the colloidally stabilizedlatex may include an aliphatic conjugated diene monomer and a at leastone additional monomer comprising a non-aromatic unsaturated mono- ordi-carboxylic ester monomer, an aromatic unsaturated monomer, at leastone nitrogen-containing monomer, or combinations thereof. Examples ofsuitable aliphatic conjugated diene monomers include C₄ to C₉ dienessuch as butadiene monomers, e.g., 1,3-butadiene, 2-methyl-1,3-butadiene,2 chloro-1,3 butadiene, 2-methyl-1,3-butadiene, and 2chloro-1,3-butadiene. Blends or copolymers of the diene monomers mayalso be used. Examples of suitable non-aromatic unsaturatedmonocarboxylic ester monomers include acrylates, methacrylates, andcombinations thereof. The acrylates and methacrylates may includefunctional groups such as amino groups, hydroxy groups, and epoxygroups. Examples of suitable non-aromatic unsaturated dicarboxylic estermonomers include alkyl and dialkyl fumarates, itaconates, maleates, andcombinations thereof, with the alkyl group having from one to eightcarbons. In a preferred embodiment, a non-aromatic unsaturatedmonocarboxylic ester monomer employed in the colloidally stabilizedlatex is methyl methacrylate. Examples of suitable aromatic unsaturatedmonomers include styrene and styrene derivatives such asalphamethylstyrene, p-methyl styrene, divinyl benzene, vinyltolunene,divinyl toluene, ethylstyrene, tert-butyl styrene, monochlorostyrene,dichlorostyrene, vinyl benzyl chloride, fluorostyrene, alkoxystyrenes(e.g., paramethoxystyrene), and combinations thereof. In a preferredembodiment, an aromatic unsaturated monomer included in the colloidallystabilized latex is styrene. Examples of suitable nitrogen-containingmonomers include acrylonitrile, methacrylonitrile, acrylamide,methacrylamide, N-methylolacrylamide, alkylated N-methylolacrylamidessuch as N-methoxymethylacrylamide and N-butoxymethylacrylamide,acrolein, and combinations thereof. In a preferred embodiment, anitrogen-containing monomer included in the colloidally stabilized latexis acrylonitrile.

In one embodiment, the colloidally stabilized latex also includes asurfactant having ethylenic unsaturation, an oxyalkylene functionalmonomer, or combinations thereof incorporated in the backbone of thepolymer. The surfactant is copolymerized with the aliphatic conjugateddiene monomer and the additional monomer and is preferably located atthe surface of the polymer particles. Since the surfactant is anintegral part of the polymer, it most likely cannot desorb from thepolymer. Examples of suitable surfactants are disclosed in U.S. Pat. No.5,296,627, which is incorporated by reference herein in its entirety.The surfactant preferably has a hydrophobic portion that possessesterminal ethylenic unsaturation and a hydrophilic portion that containsa poly(alkyleneoxy) segment. Examples of suitable oxyalkylene functionalmonomers include monoesters of carboxylic acid or dicarboxylic acid,diesters of dicarboxylic acid, compounds generally represented by thefollowing formulas, and combinations thereof:

where R is hydrogen or a C₁-C₄ alkyl, R′ is hydrogen or a C₁-C₄ alkyl,R″ is hydrogen or a C₁-C₄ alkyl, and n is in a range of from 1 to 30.The oxyalkylene functional monomer is copolymerized with the aliphaticconjugated diene monomer and the additional monomer. Additional examplesof surfactants and oxyalkylene functional monomers that may be employedin the colloidally stabilized latex are provided in aforementioned U.S.Pat. No. 5,900,451.

In the foregoing embodiment in which the colloidally stabilized latexincludes a surfactant having ethylenic unsaturation and/or anoxyalkylene functional monomer, the amount of protective colloid presentin the colloidally stabilized latex is preferably in the range of fromabout 0.1 percent (hereinafter “%”) to about 10% by total weight of thestarting monomers, more preferably from about 1% to about 8%, and mostpreferably from about 2% to about 6%. The amount of aliphatic conjugateddiene monomer present in the colloidally stabilized latex is preferablyin the range of from about 5% to about 95% by total weight of thestarting monomers, more preferably from about 20% to about 80%. Theamount of non-aromatic unsaturated mono- or di-carboxylic ester monomerpresent in the colloidally stabilized latex is preferably in the rangeof from about 5% to about 95% by total weight of the starting monomers,more preferably from about 20% to about 80%. The amount of aromaticunsaturated monomer present in the colloidally stabilized latex ispreferably in the range of from about 5% to about 95% by total weight ofthe starting monomers, more preferably from about 20% to about 80%. Theamount of nitrogen-containing monomer present in the colloidallystabilized latex is preferably in the range of from about 5% to about95% by total weight of the starting monomers, more preferably from about20% to about 80%. The amount of surfactant present in the colloidallystabilized latex is preferably in the range of from about 0.1% to about5% by total weight of the starting monomers, more preferably from about1% to about 4%, and most preferably from about 2% to about 3%. Theamount of oxyalkylene functional monomer present in the colloidallystabilized latex is preferably in the range of from about 0.1% to about7% by total weight of the starting monomers, more preferably from about1% to about 3%. When the surfactant and the oxyalkylene functionalmonomer are both used, the colloidally stabilized latex preferablycontains from about 0.5% to about 2% of the surfactant and from about 1%to about 3% of the oxyalkylene functional monomer by total weight of thestarting monomers.

In another embodiment, the colloidally stabilized latex includes afunctionalized silane incorporated in the polymer that is capable ofadsorbing the protective colloid. Examples of suitable functionalizedsilanes are generally represented by the following formula:

where R″ is a C₁ to C₅ alkyl, R′ is a C₁ to C₅ alkyl, R is SH, CH₂═CH—,CH₂═C(CH₃)—C(O)O—, CH₂═CH—C(O)O—, and

n is in a range of from 1 to 10, and m is 2 or 3. A preferredfunctionalized silane is gamma mercaptopropyl trimethoxy silane in whichR is SH, R′ is C₁ alkyl, n is 3, and m is 3. Unsaturated mono- ordi-carboxylic acid monomers and derivatives thereof, such as acrylicacid, methacrylic acid, itaconic acid, fumaric acid, and malieic acid,may also be employed in the colloidally stabilized latex. Additionalexamples of surfactants and oxyalkylnlene functional monomers that maybe employed in the colloidally stabilized latex are provided inaforementioned U.S. Pat. No. 6,130,287.

In the foregoing embodiment in which the colloidally stabilized latexincludes a functionalized silane, the amount of protective colloidpresent in the latex is preferably in the range of from about 1 percent(hereinafter “%”) to about 10% by total weight of the starting monomers.The amount of aliphatic conjugated diene monomer present in thecolloidally stabilized latex is preferably in the range of from about 1%to about 99% by total weight of the starting monomers, more preferablyfrom about 10% to about 70%, and most preferably from about 20% to about50%. The amount of non-aromatic unsaturated mono- or di-carboxylic estermonomer present in the colloidally stabilized latex is preferably in therange of from about 1% to about 99% by total weight of the startingmonomers, more preferably from about 50% to about 80%. Thefunctionalized silane may be present in the colloidally stabilized latexin various amounts. For example, the amount of silane present in thepolymer may range from about 0.01% to about 2% by total weight of thestarting monomers, preferably about 0.5%.

In yet another embodiment, when the colloidally stabilized latexcomposition contains cross-linkable monomers such asN-methylolacrylamide and alkylated N-methylolacrylamides such asN-methoxymethylacrylamide and N-butoxymethylacrylamide, appropriateacidic catalysts may be included in the latex to serve as crosslinkingagents. Such acidic catalysts provide for the formation of a resilientrubbery mass. Examples of suitable acidic catalysts include para-toluenesulfonic acid, an ammonium salt such as ammonium sulfate, ammoniumchloride, ammonium acetate, and combinations thereof. In an embodimentin which the colloidally stabilized latex contains both a vulcanizablemonomer and a crosslinkable monomer, it may further include avulcanizing agent in addition to the acidic catalyst. In anotherembodiment, the colloidally stabilized latex may include thermosettingresins such as melamine-formaldehyde derived resins andurea-formaldehyde resins that are capable of participating in thecrosslinking reactions in the presence of the acidic catalysts.

The colloidally stabilized latex may further include additionaladditives as deemed appropriate by one skilled in the art. For example,crosslinking agents, additional monomers, initiators, reducing agents,and so forth may be employed to improve the properties of the latexand/or to facilitate the polymerization of the monomers employed in thelatex.

In addition to the colloidally stabilized latex, the sealantcompositions may optionally comprise a cement slurry. A known cement maybe used in the cement slurry, including hydraulic cement containingcalcium, aluminum, silicon, oxygen, and/or sulfur, which sets andhardens by reaction with water. Examples of suitable hydraulic cementsinclude Portland cements, pozzolana cements, gypsum cements, phosphatecements, high alumina content cements, silica cements, and highalkalinity cements. The cement slurry also contains a sufficient amountof fluid to form a pumpable slurry. The fluid may be, for example, freshwater or salt water such as an unsaturated aqueous salt solution or asaturated aqueous salt solution, e.g., brine or seawater. The amount ofwater utilized in the cement slurry may range, for example, from about30% to about 150% by weight of the cement, more preferably from about35% to about 60% by weight of the cement. The relative amounts of thecolloidally stabilized latex and the cement in a particular sealantcomposition depend upon the intended use of the resulting composition.For example, the sealant compositions may contain from about 0.01 gallonto about 3.0 gallons of colloidally stabilized latex per 100 pounds ofcement, more preferably from about 0.5 gallons to about 2 gallons per100 pounds of cement. The cement, fluid, and the sealant composition maybe combined in any suitable order. For example, the sealant compositionmay be combined with the fluid before adding cement to the resultingmixture. Alternatively, the cement and the fluid may be combined to forma cement slurry before adding the sealant composition to the cementslurry. Examples of suitable sealant compositions comprising hydrauliccement are disclosed in U.S. Pat. No. 5,588,488, which is incorporatedby reference herein in its entirety.

The sealant compositions may also include salts of monovalent (e.g.,Na⁺), divalent (e.g., Ca²⁺), and trivalent cations. In an embodiment,the sealant compositions are saturated with such salts to ensure thatthey do not wash out or dissolve salt zones located in the subterraneanformation. The colloidally stabilized latex has a relatively hightolerance to salts. Thus, it desirably remains stable in the presence ofthe salts contained in the sealant compositions and in the presence ofsalts that it may encounter in the wellbore without the need tointroduce additional stabilizing surfactants, e.g., ethyoxylatednonylphenol surfactant, to the sealant compositions. It is understoodthat, if desired, such stabilizing surfactants still may be employed inthe sealant compositions and may be distinguished from ethylenicallyunsaturated surfactants incorporated in the backbone of the latexpolymer.

In an embodiment, the sealant composition may include the followingcomponents: vulcanizable groups such as the diene type of monomersdiscussed above, e.g., butadiene; vulcanizing agents such as sulfur,2,2′-dithiobisbenzothiazole, organic peroxides, azo compounds,alkylthiuram disulfides, and selenium phenolic derivatives;vulcanization accelerators such as fatty acids such as stearic acid,metallic oxides such as zinc oxide, aldehyhyde amine compounds,guanidine compound, and disulfide thiuram compounds; vulcanizationretarders such as salicylic acid, sodium acetate, phthalic anhydride,and N-cyclohexyl thiophthalimide; defoamers; fillers to increase ordecrease the treatment density as required; co combinations thereof.Additional disclosure regarding suitable latexes containing suchmaterials can be found in U.S. Pat. Nos. 5,293,938 and 5,159,980, eachof which is incorporated by reference herein in its entirety.

As deemed appropriate by one skilled in the art, the sealantcompositions may further include additional additives for improving orchanging the properties of the compositions. For example, beads andfibers, such as carbon fibers or WOLLASTOCOAT fibers commerciallyavailable from NYCO Minerals, Inc. of Willsboro, N.Y., may be includedin the sealant compositions to improve their mechanical properties suchas tensile strength, compressive strength, and so forth. Examples ofother additives include, but are not limited to, set retarders,dispersing agents, set accelerators, and defoamers.

According to an embodiment, methods of using a previously describedsealant composition to service a wellbore that penetrates a subterraneanformation include displacing the composition into the wellbore to allowit to be used for its intended purpose. As described previously, thecolloidally stabilized latex contained in the sealant compositionpreferably remains stable in the presence of salts that it contacts asit passes through the wellbore. That is, the colloidally stabilizedlatex remains dispersed in its aqueous solution and thus does notseparate out into a rubbery mass or layer.

In an embodiment, the foregoing sealant compositions that include thecolloidally stabilized latex and the cementitious material may beemployed in well completion operations such as primary and secondarycementing operations. In primary cementing, such a sealant compositionmay be displaced into an annulus of the wellbore and allowed to set suchthat it isolates the subterranean formation from a portion of thewellbore. The sealant composition thus forms a barrier that preventsfluids in that subterranean formation from migrating into othersubterranean formations. Within the annulus, the sealant compositionalso serves to support a conduit, e.g., casing, in the wellbore. In oneembodiment, the wellbore in which the sealant composition is positionedbelongs to a multilateral wellbore configuration. A multilateralwellbore configuration includes at least two principal wellboresconnected by one or more ancillary wellbores. In secondary cementing,the sealant composition may be strategically positioned in the wellboreto plug a void or crack in the conduit, to plug a void or crack in thehardened sealant, e.g., cement sheath, residing in the annulus, to pluga relatively small opening known as a microannulus between the hardenedsealant and the conduit, and so forth. Various procedures that may befollowed to use the sealant composition in a wellbore are described inU.S. Pat. No. 5,346,012, which is incorporated by reference herein inits entirety, and previously incorporated U.S. Pat. No. 5,588,488.

In another embodiment, the foregoing sealant compositions that containthe colloidally stabilized latex but no cementitious material may beutilized in well completion operations such as primary operations. Forexample, they may be placed behind expandable casings or used forconsolidating gravel packs or incompetent formations. Further, suchsealant compositions may be utilized in remedial operations such assealing leaks, cracks, or voids and forming temporary plugs for thepurpose of isolating zones to divert subsequent fluids and the like.Additional disclosure regarding the use of cementless sealantcompositions for such applications can be found in previouslyincorporated U.S. Pat. No. 5,159,980 and U.S. Pat. No. 6,668,928, whichis incorporated by reference herein in its entirety.

In yet another embodiment, a previously described sealant compositioncontaining a colloidally stabilized latex may be used to prevent theloss of non-aqueous drilling fluids into loss-circulation zones such asvoids, vugular zones, and natural or induced fractures while drilling.The sealant composition and the drilling fluid may be pumped as twoseparate, parallel streams and allowed to mix downhole near theloss-circulation zone. When the two fluids contact each under atdownhole conditions, they form a relatively viscous mass inside theloss-circulation zone. This mass plugs the zone and thus inhibits lossof subsequently pumped drilling fluid, thereby allowing for furtherdrilling. Additional disclosure regarding this application of sealantcompositions can be found in U.S. Pat. No. 5,913,364, which isincorporated by reference herein in its entirety. The drilling fluid mayinclude a non-aqueous fluid such as a diesel, a mineral oil, an internalolefin, a linear alpha-olefin, an ester, or combinations thereof. It mayalso contain organophilic clay, an emulsified brine phase, anemulsifier, a viscosifier, a weighting agent such barium sulfate, orcombinations thereof. Suitable sealant compositions for this applicationmay include an organophilic clay, a basic salt, surfactants, andadditional water as additives. Such compositions are described inpreviously incorporated U.S. Pat. No. 5,588,488. The sealantcompositions may also contain thermosetting resins such asmelamine-formaldehyde derived resins, phenol-formaldehyde derivedresins, and urea-formaldehyde derived resins for improving themechanical properties of the solid mass such as compressive and tensilestrengths. The sealant compositions may further contain curing catalystssuch as para-toluenesulfonic acid, ammonium salts, magnesium salts, andbasic salts. Such compositions are discussed in U.S. Pat. No. 6,508,306,which is incorporated by reference herein in its entirety.

EXAMPLES

The invention having been generally described, the following examplesare given as particular embodiments of the invention and to demonstratethe practice and advantages hereof. It is understood that the examplesare given by way of illustration and are not intended to limit thespecification or the claims to follow in any manner.

Example 1

First, LATEX 2000 latex sold by Halliburton Energy Services, Inc. (i.e.,a styrene butadiene latex prepared by conventional methods) was addeddropwise to an aqueous solution containing 25 weight (wt.) % sodiumchloride (NaCl) salt. Instantaneous precipitation was observed uponcontact of the latex with the salt solution. The same procedure was thenperformed using 10 mL of BS 2100 latex, i.e., a colloidally stabilizedlatex. No precipitation was observed in the solution containing the BS2100 latex even after several days.

Example 2

A 40 gram mixture containing a 1:1 weight ratio of LATEX 2000 latex andwater was prepared. Then 33 wt.% calcium chloride (CaCl₂) solution inwater was added dropwise to the latex-containing solution. Most of theLATEX 2000 latex had precipitated out of the solution after 0.7 gram ofthe CaCl₂ salt had been added to the solution. The same procedure wasthen performed using BS 2100 latex. No sign of precipitation wasobserved even after 10 grams of CaCl₂ salt had been added to thesolution containing BS 2100 latex, and the mixture was stable forseveral days.

Example 3

A control sample of a cement slurry having a density of 16.4 pounds pergallon (ppg) and comprising LATEX 2000 latex, water, class H Portlandcement, and a small amount of a STABILIZER 434B surfactant stabilizeravailable from Halliburton Energy Services, Inc. was prepared. Thecontrol sample was cured for 72 hours at a temperature of 190° F. and apressure of 3,000 psi, followed by measuring, compressive strength andtensile strength. The same properties were measured for a control sampleof the same density made from cement and water. In addition, two cementslurry samples containing BS 2100 latex, water, and class H Portlandcement were prepared. One sample also contained a small amount ofSTABILIZER 434C surfactant stabilizer and the other sample containedWOLLASTOCOAT M16 fibers (i.e., a wollastonite mineral coated with anorganic hydrophobic material). After curing those samples in the samemanner as the control sample was cured the compressive strength and thetensile strength of those samples were also measured. All the slurrieswere prepared and the compressive strengths were measured according toAPI Recommended Practice 10B, Twenty-Second Edition, December 1997. Thetensile strengths were measured using a briquette mold procedureaccording to ASTM C 190-85 (outdated). The relative amounts of thesamples used in this example and the values of the mechanical propertiestaken for the samples are shown in Table 1 below.

TABLE 1 Stabilizer Surfactant, gallon/sack BS 2100 Compressive TensileWater, % of cement latex, Density, Strength, Strength, Sample bwoc²(gal/sk) gal/sk Other Additives ppg psi psi 1¹ 33.20 0.07 — LATEX 200016.31 3,880 470 (control) latex, 0.7 gal/sk 2 39.42 — — — 16.4 4,340 430(control) 3¹ 33.20 0.07 0.74 16.32 5,490 600 4¹ 33.20 — 0.74WOLLASTOCOAT 16.4 4,390 570 M15³, 0.75% bwoc ¹Contained 0.02 gal/sk ofD-AIR 3000 defoamer available from Halliburton Energy Services, Inc.²Does not include the water present in the latex and surfactantsolutions; bwoc = by weight of the cement

As shown in Table 1, the compressive strength and the tensile strengthof the cement slurry samples containing the BS 2100 latex were higherthan those of the control samples. The results in Table 1 thus show thatthe mechanical properties of set cement samples can be improved relativeto control samples with or without traditional latex.

Example 4

Cement slurries of 16.4 ppg density were prepared according to theformulations listed in Table 2, and each additionally contained 0.05gallon/sack D-AIR 3000L defoamer and HR-6L retarder, both of which areavailable from Halliburton Energy Services, Inc. All of the ingredientsexcept cement were added to mix water, followed by the addition ofcement according to the previously mentioned API procedure. Not listedin Table 2 are slurries the preparation of which was attempted usingLATEX 2000 latex. Those non-listed slurries were identical to controlslurries #1 and #2 except that the STABILIZER 434B surfactant was leftout. Upon stirring, the non-listed slurries became too viscous, gelledquickly, and thus could not be used.

The slurries were placed in an atmospheric consistomer preheated to 190°F. and stirred at 100 rpm for 20 minutes. The initial and finalviscosity after 20 minutes were measured in Bearden units (Bc). Thesemeasured values indicated the pumpability and response of the slurryviscosity to heating. The heated slurry was then subjected to fluidmeasurement according to the previously mentioned API procedure. Also,using another sample that had been preheated to 190° F., the rheology atdifferent shear rates was measured using a Fann 35 viscometer at 190° F.The results are provided in Table 3.

TABLE 2 Latex Dispersant Sample Water, Latex Amount, Surfactant,Dispersant Amount, Salt, No. % bwoc Type gal/sk gal/sk Type gal/sk %bwow 1 26.7 LATEX 2000 1 0.2 CFR-3L¹ 0.143 None (Control) 2 30.7 LATEX2000 1 0.2 CFR-3L 0.143 18 (Control) 3 29.9 LATEX 2000 1 0.2 None — 18(Control) 4 29.03 BS 2100 1 None MEGAPOL MP² 0.06 None 5 31.3 BS 2100 1None MEGAPOL MP 0.06 18 ¹Available from Halliburton Energy Services,Inc. ²Available from Handi Chemicals Limited, Candiac, Canada

TABLE 3 Fann Rheology @ 600-300-200- 100-60-30-20- Fluid Loss, SampleViscosity, Bc 10-6-3 rpm cc/30 min. Sample 1 Initial - 3; Final - 423-15-8-5-4-2-2-1.5-1  72 (Control) Sample 2 Initial - 3; Final - 419-12-7-5-4-3-2-1-1  88 (Control) Sample 3 Initial - 4; Final - 420-14-8-5-4-3-2-1-1  139¹ (Control) Sample 4 Initial - 4; Final - 523-14-7-4-3-2-1.5-1-1  217¹ Sample 5 Initial - 8; Final - 1078-58-39-31-24-  584¹ 22-16-14-12 ¹The fluid loss value was calculatedaccording to the previously mentioned API procedure after collecting thefiltrate for a period

As shown in Table 3, the colloidally stabilized latex containingslurries exhibited satisfactory fluid loss values. The results in Table3 show that useable slurries can be made with colloidally stabilizedlatex without needing latex stabilizing surfactants.

Example 5

Slurries of 12.0 ppg were prepared according to the formulations shownin Table 4. They were cured and analyzed for compressive and tensilestrengths as described in Example 3.

TABLE 4 Class H Fumed Latex BS Compr. Tens. cement, % Flyash¹, silica²,Bentonite, 2000, 2100 Surfacant³ Strength, Strength, bwoc % bwoc % bwoc% bwoc gal/sk gal/sk gal/sk Psi psi 56 22 22 2 0.75 0.15 1020 100 56 2222 2 0.75 0.15 1780 95 ¹Class F microflyash available from HalliburtonEnergy Services, Inc. ²Available from Halliburton Energy Services, Inc.under the tradename SILICALITE fumed silica ³Available from HalliburtonEnergy Services, Inc. under the tradename STABILIZER 434C surfactantThe results in Table 4 show that the mechanical properties of cementslurries containing pozzalonic materials can also be improved withcolloidally stabilized latexes.

Example 6

An equal volume of oil-based mud available from Baroid Drilling Companywas added to a mixture of LATEX 2000 latex diluted with an equal volumeof water, organophilic clay (28% by weight of the latex mixture), and aSTABILIZER 434C surfactant (6% by weight of the latex mixture). Themixture underwent viscosification, and a solid with moldable consistencywas formed within 2 minutes. The composition was cured at 180° F. for 18hours. A second composition with an identical mixture was made byreplacing LATEX 2000 latex with a JG 6092-99-00 colloidally stabilizedstyrene-butadiene based latex obtained from Dow Reichhold Corp., exceptthat the stabilizing surfactant was left out. The compositionviscosified in about 3 minutes and formed a moldable mass. The materialwas cured at 180° F. for 18 hours. The results indicated that mixingoil-based muds with the compositions containing colloidally stabilizedlatex quickly forms competent viscous masses without the need for alatex stabilizing surfactant, thus preventing drilling fluid circulationlosses.

Example 7

A mixture containing BS 2100 colloidally stabilized latex and water at aweight ratio of 1:1 was mixed with para-toluenesulfonic acid (10% byweight of the active polymer content of the latex) and heated at 195° F.for 48 hrs. The latex cross-linked, and a homogeneous rubbery mass ofcured solid with a trace of free water formed. This result indicates theability of colloidally stabilized latexes provided with cross-linkablefunctional groups to form resilient compositions that are useful inapplications such as sealant systems for multilateral wells, expandabletubulars, and the like.

While preferred embodiments of the invention have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the invention. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the inventiondisclosed herein are possible and are within the scope of the invention.Use of the term “optionally” with respect to any element of a claim isintended to mean that the subject element is required, or alternatively,is not required. Both alternatives are intended to be within the scopeof the claim.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present invention. Thus, the claims are a further description andare an addition to the preferred embodiments of the present invention.The discussion of a reference in the Description of Related Art is notan admission that it is prior art to the present invention, especiallyany reference that may have a publication date after the priority dateof this application. The disclosures of all patents, patentapplications, and publications cited herein are hereby incorporated byreference, to the extent that they provide exemplary, procedural orother details supplementary to those set forth herein.

1. A method of servicing a wellbore in contact with a subterraneanformation, comprising: placing a sealant composition comprising acolloidally stabilized latex into the wellbore and contacting thesealant composition with salt as it passes through the wellbore, whereinthe collodially stabilized latex comprises a protective colloidcomprising polyvinylalcohol, a cellulose ether, a natural gum, asynthetic gum, polyacrylic acid, an acrylate, a poly(vinylalcohol)co(vinyl amine) copolymer, or combinations thereof and does notprecipitate in a solution of at least 25 weight percent salt.
 2. Themethod of claim 1, wherein the colloidally stabilized latex comprises:(a) an aliphatic conjugated diene monomer; and (b) an additional monomercomprising a non-aromatic unsaturated mono- or di-carboxylic estermonomer, an aromatic unsaturated monomer, a nitrogen-containing monomer,or combinations thereof.
 3. The method of claim 2, wherein thecolloidally stabilized latex comprises a functionalized silane generallyrepresented by:

wherein R″ is a C₁ to C₅ alkyl, R′ is a C₁ to C₅ alkyl, R is SH,CH₂═CH—, CH₂═C(CH₃)—C(O)O—, CH₂═CH—C(O)O—, or

n is in a range of from 1 to 10, and m is 2 or
 3. 4. The method of claim3, wherein the sealant composition comprises cement.
 5. The method ofclaim 3, wherein the sealant composition comprises fibers, beads, orcombinations.
 6. The method of claim 2, wherein the colloidallystabilized latex comprises a surfactant having ethylenic unsaturationthat copolymerizes with the aliphatic conjugated diene monomer and theadditional monomer, thereby forming a polymer having the surfactant inits backbone.
 7. The method of claim 2, wherein the sealant compositioncomprises cement.
 8. The method of claim 2, wherein the sealantcomposition comprises fibers, beads, or combinations.
 9. The method ofclaim 1, wherein the colloidally stabilized latex comprises anoxyalkylene functional monomer comprising

a monoester of mono- or di-carboxylic acid, a diester of dicarboxylicacid, or combinations thereof, wherein R is hydrogen or a C₁-C₄ alkyl,R′ is hydrogen or a C₁-C₄ alkyl, R″ is hydrogen or a C₁-C₄ alkyl, and nis in a range of from 1 to 30, and wherein the oxyalkylene functionalmonomer copolymerizes with the aliphatic conjugated diene monomer andthe additional monomer.
 10. The method of claim 9, wherein the sealantcomposition comprises cement.
 11. The method of claim 9, wherein thesealant composition comprises fibers, beads, or combinations.
 12. Themethod of claim 1, wherein the salt comprises a monovalent ion, adivalent ion, or combinations thereof.
 13. The method of claim 12,wherein the sealant composition is displaced into an annulus of thewellbore and allowed to set.
 14. The method of claim 12, wherein thesealant composition comprises cement.
 15. The method of claim 12,wherein the sealant composition comprises fibers, beads, orcombinations.
 16. The method of claim 1, wherein the sealant compositioncomprises fibers, beads, or combinations thereof.
 17. The method ofclaim 16, wherein the sealant composition comprises fibers, beads, orcombinations.
 18. The method of claim 1, wherein the sealant compositioncomprises a cement slurry.
 19. The method of claim 1, wherein thesealant composition is positioned in the wellbore to isolate thesubterranean formation from a portion of the wellbore, to support aconduit in the wellbore, to plug a void or crack in the conduit, to pluga void or crack in a cement sheath disposed in an annulus of thewellbore, to plug an opening between the cement sheath and the conduit,or combinations thereof.
 20. The method of claim 1, wherein thecolloidally stabilized latex comprises a vulcanizable group, avulcanizing agent, a vulcanization accelerator, a vulcanizationretarder, or combinations thereof.
 21. The method of claim 20, whereinthe sealant composition comprises cement.
 22. The method of claim 20,wherein the sealant composition comprises fibers, beads or combinations.23. The method of claim 1, wherein the colloidally stabilized latexcomprises a crosslinkable monomer, an acidic catalyst, a thermosettingresin, or combinations thereof.
 24. The method of claim 23, wherein thesealant composition comprises cement.
 25. The method of claim 23,wherein the sealant composition comprises fibers, beads, orcombinations.
 26. The method of claim 1, further comprising combining adrilling fluid with the sealant composition near a loss-circulationzone, thereby forming a solid mass in the loss-circulation zone.
 27. Themethod of claim 26, wherein the sealant composition comprises cement.28. The method of claim 26, wherein the sealant composition comprisesfibers, beads, or combinations.
 29. The method of claim 1, wherein thesealant composition comprises cement.
 30. The method of claim 1, whereinthe sealant composition comprises fibers, beads, or combinations. 31.The method of claim 1, wherein the wellbore service comprises primarycementing in the wellbore.
 32. The method of claim 1, wherein thewellbore service comprises secondary cementing in the wellbore.
 33. Themethod of claim 1, wherein the wellbore service comprises remediatinglost circulation while drilling.